The Queen’s younger sister was told that she would have to renounce her rights of succession in order to go through with the wedding, and ultimately chose to stay true to “the Church's teachings that Christian marriage is indissoluble”.

The move sparked a constitutional crisis due to the Church of England’s teaching that remarriage is not allowed if the former spouse is still alive.

In the decades since, the Church and the Royal Family have modernised their attitudes to marriage.

In 2005, the Queen gave permission for Prince Charles to marry fellow divorcée Camilla Parker Bowles, now the Duchess of Cornwall.

Prince Harry's girlfriend Meghan Markle
Tue, November 8, 2016

Prince Harry confirms he is in a relationship with model and actress Meghan Markle

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Prince Harry's girlfriend Meghan Markle

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Meghan has previously been married

While the monarch did not attend the couple’s civil ceremony, she and Prince Philip held a reception for them at Windsor Castle.

Constitutionally, Harry would still need the Queen’s approval before any wedding could be planned.

The Perth agreement of 2011 decrees that the first six in line to the throne need sovereign approval to marry. Harry is currently fifth-in-line, but could be pushed down should Prince William and Kate decide to expand their brood.

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Meghan stars in legal drama Suits

Although Meghan and Harry spent New Year’s together, the actress was not invited to spend Christmas with the Royal Family at Sandringham.

While some took Meghan’s absence as a possible sign of the Queen’s disproval, royal expert Katie Nicholl explained that it was simply down to protocol.

“Harry knows the rules of the Royal Family and he knows that until they get engaged, Meghan will not have a place around that Christmas dinner table,” she told ET Online.